Cooling fluidized catalytic cracking regeneration zones with heat pipe apparatus

Abstract

An apparatus is presented for burning carbonaceous deposits off of fluidized particles. The apparatus is preferably employed as the catalyst regeneration zone of a fluidized catalytic cracking process. Heat pipes are used to cool the particles and transfer heat to an external steam generation zone. Preferably, the heat pipes extend vertically upward from an external catalyst transfer conduit to the steam generation chamber. The water level in the steam generation chamber or the density of the fluidized particles in contact with the heat pipes can be used to control the rate of heat removal from the combustion zone.

I claim as my invention: 
     
       1. An apparatus for the combustion of carbonaceous materials present on fluidizable particles employed in a hydrocarbon conversion process which comprises: (a) means for confining a fluidized mass of said particles comprising a chamber, a particle inlet, a particle outlet, an oxygen-containing gas inlet and a flue gas outlet, with the flue gas outlet communicating with an upper end of the chamber;   (b) a steam generating chamber having associated therewith a means to charge liquid water to the steam generation chamber and remove steam from an upper end of the steam generation chamber at a point above a level at which water would rest in a lower portion of the chamber; and,   (c) a plurality of heat pipes, each heat pipe having a lower first end located within said means for confining the fluidized mass of particles and an upper second end located within said steam generation chamber.   
     
     
       2. The apparatus of claim 1 further characterized in that said means for confining the fluidized mass of particles comprises both an upper chamber and a lower chamber and means to transfer particles upward from the lower chamber to the upper chamber by fluidization in a gas stream. 
     
     
       3. The apparatus of claim 2 further characterized in that the first end of said heat pipes is located within said upper chamber. 
     
     
       4. The apparatus of claim 2 further characterized in that said means for confining the fluidized mass of particles also comprises a particle circulation conduit located external to the upper and lower chambers and providing a vertical flow path between the upper and lower chambers. 
     
     
       5. The apparatus of claim 4 further characterized in that the first end of said heat pipes is located within said upper chamber. 
     
     
       6. The apparatus of claim 4 further characterized in that the first end of said heat pipes is located within the particle circulation conduit. 
     
     
       7. The apparatus of claim 6 further characterized in that the steam generation chamber is located above the portion of the particle circulation conduit which contains the first end of said heat pipes. 
     
     
       8. The apparatus of claim 2 further characterized in that the apparatus is a catalyst regeneration zone of a fluidized catalytic cracking process. 
     
     
       9. The apparatus of claim 1 further characterized in that the apparatus also comprises means to regulate heat transfer by the heat pipes comprising a means to control the level of liquid-phase water in contact with said heat pipes in the steam generation chamber. 
     
     
       10. An apparatus for the regeneration of catalyst used in a fluidized catalytic cracking process which comprises: (a) an upper chamber, with means being provided to withdraw a flue gas stream from an upper portion of the upper chamber and to withdraw regenerated particles from a lower portion of the upper chamber;   (b) a lower chamber, with means being provided to pass used catalyst and an oxygen-containing gas stream into the lower chamber;   (c) means to transfer fluidized catalyst upward from the lower chamber into the upper chamber;   (d) a particle circulation conduit located externally to the upper and lower chambers, with the particle circulation circuit extending downward from a lower portion of the upper chamber to the lower chamber;   (e) a steam generation chamber located outside of the upper and lower chambers; and   (f) a plurality of heat pipes having a lower first end located in said particle circulation conduit and an upper second end located in said stream generation chamber, with a steam removal conduit being attached to the steam chamber at a point above the heat pipes.   
     
     
       11. The apparatus of claim 10 further characterized in that the steam generation chamber is located above substantially all of the particle circulation conduit. 
     
     
       12. The apparatus of claim 11 further characterized in that the heat pipes have a substantially vertical orientation. 
     
     
       13. The apparatus of claim 11 further characterized in that a particle flow control means is located within the particle circulation conduit. 
     
     
       14. The apparatus of claim 10 further comprising means to control the liquid phase water level within the steam generation chamber. 
     
     
       15. The apparatus of claim 14 further comprising a means to supply a fluidizing gas into a lower portion of the particle circulation conduit. 
     
     
       16. The apparatus of claim 10 further characterized in that the apparatus comprises a means to pass an oxygen-containing gas stream into the upper chamber. 
     
     
       17. The apparatus of claim 16 further characterized in that the apparatus comprises a means to separately withdraw a second flue gas stream from said lower chamber. 
     
     
       18. The apparatus of claim 10 further characterized in that the apparatus comprises a means to regulate the rate of heat transfer through said heat pipes from the particle circulation conduit to the steam generation chamber which comprises a means to control the level of liquid-phase water in contact with said heat pipes in the steam generation chamber. 
     
     
       19. An apparatus for the regeneration of catalyst used in a fluidized catalytic cracking process which comprises: (a) a means for confining a fluidized bed of catalyst comprising a vertically aligned first cylindrical chamber, a catalyst inlet conduit, a catalyst outlet conduit, an inlet conduit for an oxygen-containing gas stream and a flue gas outlet conduit;   (b) a catalyst cooling chamber located outside said means for confining a fluidized bed of catalyst;   (c) a catalyst transfer conduit extending between said first chamber and said catalyst cooling chamber;   (d) a steam generation chamber;   (e) a plurality of heat pipes, each heat pipe haivng a lower first end located within said catalyst cooling chamber and an upper second end located within the steam generation chamber and,   (f) means to charge liquid water to the steam chamber and to collect and remove steam from the steam chamber at a point above the heat pipes.   
     
     
       20. The apparatus of claim 19 further characterized in that the catalyst cooling chamber is vertically aligned. 
     
     
       21. The apparatus of claim 20 further characterized in that the catalyst transfer conduit is attached to an upper end of the catalyst cooling chamber. 
     
     
       22. The apparatus of claim 21 further characterized in that the steam generation chamber is superjacent the catalyst cooling chamber. 
     
     
       23. The apparatus of claim 22 further characterized in that a catalyst removal conduit is attached to a lower end of the catalyst cooling chamber and communicates with the means for confining a fluidized bed of catalyst at a lower elevation than said catalyst transfer conduit communicates with the first chamber thereby providing a catalyst recirculation conduit. 
     
     
       24. The apparatus of claim 19 further comprising a means for passing a fluidizing gas into the catalyst cooling chamber at a point below at least a portion of the heat pipes located within the catalyst cooling chamber. 
     
     
       25. The apparatus of claim 19 further comprising a means to control the level of liquid phase water present in the steam generation zone and to thereby regulate the amount of heat removed through the heat pipes from the catalyst cooling chamber.